I have only been to SA once so I am far from an expert on this subject but here is my 2c anyway...
In the world of freelance PH's, where a PH may only sign on for only one hunt or maybe one season, and the reality of the Outfitter business needs to have repeat clientele to survive, I can see where there would be potential for some real heartburn if PH's poach their previous Employers clients behind that Outfitters back.
In today's world of instant communication there is realistically no way for anyone to prevent two people who want to communicate from doing so. And I think foolish to even attempt, potentially leaving a bad taste for everyone involved.
At the end of the day the PH and the Outfitter are all in the same same business and we as hunters are their customers. And as
long as there is open, honest, communication between everyone involved it will work.
But, if the Outfitter attempts to somehow restrict that communication, or a PH attempts to poach customers, or even a hunter attempts to poach a PH, it has all the potential for a least hard feelings and probebly the end of business relationships.
With all of that said, if I was planning to go back on another hunt with a PH that I hunted with before, separate from the Outfitter I used before, I would be in contact with that Outfitter well in advance to let him know what we are up too. I may even want to stop by and have a beer with him if possible.....Heck it's really just sport hunting and supposed to be fun for everyone involved. I still may want to hunt with that Outfitter again someday and have a good time. As the paying customer there is no sense in building bridges just to burn them behind me, I may want to use them again....